Speech-current apparatus



Jan. 7, 1930. ZIMMERMAN 1,743,011

SPEECH CURRENT APPARATUS Filed Feb. 14, 1928 Inventor- ArthurGZim'mePman 9 w Hi2; Afiohh eg Patented Jan. 7, 1930 UNITED STATESParser-onion ARTHUR, G. ZI-MMERMAN, or scnnnncrnnr, new YORK, ASSIGNOR13o GENERAL ELEC- 'rnro COMPANY, A oonronmnon or NEWYYORK SPEECH-CURRENTAPPARATUS Application filed February 14, 1928. Serial No. 254,296. I

My invention relates to speech current generators and motors, and hasfor its principal object the provision of an improved apparatus whichmay be eficiently operated either to convert speech current into soundor to generate electric current which is dependent on sound,

Various types of speech current have been provided in the past. Many ofthese apparatus include a coil which is mounted on a diaphragm and isarranged to move in a magnetic field either in response to speechcurrent supplied to the coil or in response to sound impulses applied tothe diaphragm. 1

As pointed out in Patent No; 1,?07,570, issued April 2, 1929, to ChesterW. Rice, and assigned to the same assignee as the present application,apparatus may be improved by the provision of conductive rings of copperor similar low resistance materials embedded in the pole pieces of themagnet through which the magnetic field surrounding the movable coil is:produced. With this construction, the con ductive rings embedded in thepole pieces form low resistance secondary circuits which reduce thereactive component oi the diaphragm coil impedance and increase the operating efiiciency of theapparatus. In ac- ,cordance with my invention,is further increased by making the conductive rings in the form oflayers of conductive material which are rolled, electroplated orothergwise placed on the active surfaces of the pole pieces. This arrangementof the conductive rings has the important advantage that it perm-itsvery close coupling between these rings and the movable diaphragmcoil,thusgreatly decreasing the inductance of the movable coil.

My invention will be better.understood from the following descriptionwhen considered in connection with the accompanying drawings and itsscope will be pointed out in the appended claims. v

. Referring to the drawings, Fig, I-is asec- 'tional view of aspeechcurrent apparatus wherein my invention has been embodied,

apparatus the operating efficiency of such this efiiciency and Figs. 2and 3 illustrate various details of the pole pieces oi this apparatus.

This apparatus includes a coil 4 which is mounted on a diaphragm 5 andis arranged to move between the pole pieces 6 and 7 of a m'agnet shownas'provided with a field or excitlngcoil' 8. As shown more clearly in Xis provided Figs. 2 and 3, the [pole piece 6 with a copper lining 9 andthe pole piece 7 is provided with a copper covering 10.

It will be readily understood that the conductive coverings 9 and 10 maybe made very thin and may extend somewhat beyond the active areas of thepole pieces so that the flux of the magnet is highly concentrated in thepath of the moving'diaphragm coil 4. Under these conditions, theapparatus has been found to operate very efficiently when utilized toconvert speech current into sound or vice versa. :While both the polepieces have been shown as" provided with a C0111 ductive covering, itshould be understood that similar results may be secured by increasingthe thickness of one of the coatings and omitting the other coating.

pair of magnetic pole-pieces, layers of con- 'ductive material arrangedto cover the active areas of both of said pole pieces, a diaphragm, anda coil mounted on said'diaphragm and arranged to move between saidlayers of conductive material. r

2. A speech current apparatus including a pair of magnetic pole pieces,layers of nonmagnetic conductive material arranged to cover the activeareas of both of said pole pieces, a diaphragm, and a .coil mounted onsaid diaphragmandarranged to move between said layers ofnon-magnetic'conductive materiah' 3.. A speech current apparatus including a pair ofmagnetic pole pieces, layers of copper arranged to cover \the activeareas of both of said pole pieces, a diaphragm, and a coil mounted onsaid diaphragm and arranged to p move between said layers of copper.

' 4. A speech current apparatus including a pair of magnetic polepieces, the active area of one of said pole pieces being electro-platedwhereby it is covered with a thin 1a. er of conductive, material, adiaphragm, an a coil mounted on said diaphragm and arranged to movebetween said pole pieces.

In witness whereof, I have hereunto set my hand this 13th day ofFebruary, 1928.

ARTHUR G. ZIMNIERMAN.

